1. Field of the Invention
The present invention relates to a flame resistant optical fiber ribbon.
2. Description of the Related Art
In recent years, an optical interconnection system using optical fibers for wiring has been attracting attention as a technology for sending a signal in a transmission device. Usually, such optical fibers are used in a form of an optical fiber ribbon. An optical fiber ribbon is formed by arranging in parallel optical fibers, each obtained by forming a fiber coating made of, for example, an ultraviolet curable resin around the circumference of a glass optical fiber, and then coating the optical fibers at the same time with a ribbon coating made of, for example, an ultraviolet curable resin. A conventional optical fiber ribbon used for the optical interconnection system is formed by, for example, arranging in parallel 12 optical fibers, each having an outer diameter of 250 μm and obtained by forming a fiber coating including a primary layer and a secondary layer on the circumference of a glass optical fiber having an outer diameter of, for example, 125 μm, at a pitch of 250 μm and then integrating the optical fibers with a ribbon coating. The conventional fiber ribbon has a thickness of about 300 μm and a width of about 3.1 mm.
To improve efficiency in installing wiring of this type of optical fibers in a transmission device, techniques for reducing the diameter of an optical fiber and the thickness of an optical fiber ribbon are under development. In addition, there has been an increasing demand for flame resistance as one characteristic of this kind of optical fiber ribbon. For example, US Patent Application No. 2006/0034575 discloses an optical fiber ribbon coated with a ribbon coating of flame resistant ultraviolet curable resin.
However, if a fiber coating and a ribbon coating are formed thinner to reduce the diameter of an optical fiber and the thickness of an optical fiber ribbon, favorable flame resistance and screening characteristics cannot be obtained.